Synthesis of new 4-(1-ethylthio-2,2,2-trifluoroethyl)-6-methylpyridazin-3(2H)-ones starting from S-ethyl 4-oxo-2-(pentafluoroethyl)pentanethiolate and hydrazines

The paper presents a one-pot conversion of γ-keto-α-pentafluoroethyl thioester into new pyridazin-3-ones and α,β-unsaturated lactams. The structures of all new compounds were ascribed using 1D (¹⁹F, ¹H, ¹³C) and 2D (¹H-¹⁵N) NMR data, and X-ray diffraction analysis. Two possible competitive reaction mechanisms for the synthesis of pyridazin-3-ones and lactams are presented.     

Synthesis of 1,3,4‐Oxadiazoles and 1,3‐Thiazolidinones Containing 1,4,5,6‐Tetrahydro‐6‐pyridazinone

The reaction of 1,4,5,6‐tetrahydro‐6‐pyridazinone‐3‐carboxylic acid hydrazides ( 1 ) with aromatic aldehydes afforded 1,4,5,6‐tetrahydro‐6‐pyridazinone‐3‐carbonyl aromatic aldehyde hydrazones ( 2a‐2g ). Heterocyclic derivatives linked 1,3,4‐oxadiazole obtained by cyclocondensation of 2a‐2g with acetic anhydride in absolute ethanol, and 2a‐2g cyclized with mercaptoacetic acid in DMF in the presence of anhydrous ZnCl₂ afforded the 1,3‐thiazolidinone derivatives. The structures of the new compounds were established by elemental analyses, IR, ¹H NMR and MS spectral data.     

Pd-catalyzed intramolecular direct arylations at high temperature

Pd-catalyzed cyclodehydrohalogenation involving oxidative addition of aromatic C-Br or activated azaheteroaromatic C-Cl bonds and C(sp²)-H activation have been investigated at high reaction temperatures (180-200 °C). This allowed the fast (10-30 min) synthesis of a variety of azaheteroaromatic ring systems (dibenzo[f,h]phthalazine, dibenzo[f,h]cinnoline, benzofuro[2,3-d]pyridazine, 5H-pyridazino[4,5-b]indole, 7H-indolo[2,3-c]quinoline and 5H-δ-carboline) in moderate to good yields.     

丁苯酞-哒嗪酮衍生物的设计、合成及其抗凝活性研究

为了提高丁苯酞的抗血小板凝集活性,以6-氨基丁苯酞为起始原料,经重氮化/还原、环化、水解、脱氯、醚化和磺酰化反应合成了20个新型的丁苯酞-哒嗪酮衍生物,其结构经1H-NMR、13C-NMR和HRMS确证。体外抗血小板凝集活性测试结果表明:化合物6a、6b和6k对二磷酸腺苷(ADP)诱导的血小板凝集的抑制活性(IC50 = 44.9-180.0 μmol/L)优于先导化合物丁苯酞(IC50 = 1252 μmol/L)和阳性对照阿司匹林(IC50 = 1140 μmol/L);同时化合物 6b(IC50 = 63.6 μmol/L)和6k(IC50 = 191.9 μmol/L)对花生四烯酸(AA)诱导的血小板凝集也表现出显著的抑制活性。本研究为丁苯酞-哒嗪酮骨架在治疗缺血性脑卒中方面的研究提供了理论参考。     

哒嗪—3—酮类化合物的合成进展

综述了近年来哒嗪酮环骨架合成方法的研究进展，包括：１）由二羰基化合物合成；２）采用环加成反应；３）杂环转化法，以及其它方法，还叙述了哒嗪酮核苷的合成，参考文献２２篇。     

Synthesis of N-Aryl-2- （1＇, 6＇-dihydro-6＇-pyridazinone-3＇-carbonyl） Thiosemicarbazides and Their Related Heterocyclic Compounds

1,6-Dihydro-3-hydrozinocarbonyl-6-pyridazinone (compound 2) were prepared from α-ketoglutaric acid and hydrazine hydrate. A series of N-aryl-2-(1‘,6‘-dihydro-6‘-pyridazinone-3‘-carbonyl) thiosemicarbazides 3a-3f were synthesized from the reaction of aryl isothiocyanates with compound 2. The terminal compounds 1,3, 4-thiadiazole, 1,3,4-oxadiazole and 1,2, 4-triazol-5-thione derivatives were cyclized from compounds 3a-3f. Their structures were confirmed by IR,^1H NMR, MS and elemental analyses.     

Synthesis of N-Aryl-2-(1′,6′-dihydro-6′-pyridazinone-3′-carbonyl) Thiosemicarbazides and Their Related Heterocyclic Compounds

Introduction Somepyridazineshavebeenexaminedforac- tivityagainstsporozoanandflagellateparasitesand forantiamebicactivity[1]. 6-Aryl-4,5-dihydro-3(2H)-pyridazinonesex- hibitvariousbiologicalpropertiesincludingreduc- tionofbloodpressure,inhibitionofplateletaggre- gation,antiinflammation,andstrongplateletag- gregationinhibitingactioncoupledwithahypoten- siveaction.Italsopossessesweakpositiveinotrop- icactivityforthemanagementofcongestiveheart failure.Threepara-substitueddihydropyridazi- nonesare…     

Effective esterification of carboxylic acids using (6-oxo-6H-pyridazin-1-yl)phosphoric acid diethyl ester as novel coupling agents

(6-Oxo-6H-pyridazin-1-yl)phosphoric acid diethyl esters (3) are efficient and selective coupling agents for equimolar esterification of carboxylic acids and alcohols. Esterification of aliphatic and aromatic carboxylic acids with aliphatic and aromatic alcohols using 3 afforded the corresponding esters chemoselectively in good to excellent yield.     

Confirmation and prevention of halogen exchange: practical and highly efficient one-pot synthesis of dibromo- and dichloropyridazinones

Commercially available anilines were converted by a two step, one-pot process to the corresponding pyridazinones in good to excellent yields. During the process research, a significant halogen exchange was confirmed and prevented which allowed the process to be scaled to multikilogram quantities.     

Efficient synthesis of 2,6-disubstituted-5-hydroxy-3-oxo-2,3-dihydro-pyridazine-4-carboxylic acid ethyl esters

A general procedure is described for the preparation of 6-substituted-5-hydroxy-3-oxo-2,3-dihydro-pyridazine-4-carboxylic acid ethyl esters (6-substituted-5-hydroxy-3(2H)-pyridazinone-4-carboxylic acid ethyl esters). These compounds are shown to undergo selective alkylation at the 2-position in moderate to good yields (19-77%) to afford 2,6-disubstituted-5-hydroxy-3-oxo-2,3-dihydro-pyridazine-4-carboxylic acid ethyl esters (2,6-disubstituted-5-hydroxy-3(2H)-pyridazinone-4-carboxylic acid ethyl esters).